/Engine/Source/Runtime/NavigationSystem/Public/NavLinkCustomComponent.h
Notify called when agent starts using this link for movement. returns true = custom movement, path following will NOT update velocity until FinishUsingCustomLink() is called on it
virtual bool OnLinkMoveStarted ( [UObject](API\Runtime\CoreUObject\UObject\UObject) * PathComp, const FVector & DestPoint )